This invention relates generally to output buffer circuits, and more particularly the invention is directed to a buffer circuit in which state transition is controlled to prevent false readings in adjacent circuitry.
The tristate buffer is drive circuitry which responds to two inputs by providing three outputs; high, low and floating. In a typical circuit a first input controls the output in either floating or responding to the second input which can be a high (+v) or a low (ground) voltage level.
When the output goes from a high (+v) to a low (ground) voltage state, a transistor responds to the second input transition and ties the output to a circuit ground terminal. However, the circuit ground terminal is tied to ground through inductive interconnections of the circuit, circuit carrier, and printed circuit board on which the carrier is mounted. Thus a voltage rise can occur at the circuit ground terminal during a high to low voltage transition which can adversely affect other buffers and circuits tied to the common circuit ground terminal.
The present invention is directed to a buffer circuit in which deleterious effects of voltage transitions are minimized.